I inspected and pictured this comb out of my top bar hive today. On zooming into the image its clear the cells have multiple new laid eggs and grubs that most likely are drones. I suspect the hive to now be queenless. Is it possible to introduce a bought in queen.
[img]https://goo.gl/photos/qqv3vF9rEE2Cf7zg9[/img]

Although I was unable to view the picture, I think it is of no use to try and save this collony. Laying workers and their brood produce queen feromones, so the collony does not consider itselves to be queenless.

Laying workers produce att max about 30 eggs each. One laying worker just lays 1 egg in a cell and the multiple eggs per cell means multiple laying workers. So the picture you discribe indicates a vast amount of laying workers.

IMHO this collony is doomed. Contrary to popular belief, laying workers can fly and find their way back if shaken off.

Even if the collony fails, the large amount of drones may contribute to the gene pool (providing you practice open mating on your apiary) so not all is lost.

I have not had much luck in sorting out a hive that has got to the stage where the workers are laying even with a shake out.

The drones are no good either as they are diploid drones from laying workers and eventually the size diminishes and they become dwarf drones...the bees are trying to do something but the process is not finished I suppose.

I too have not had success with shaking out and requeening. I think the best situation may be to remove the hive to a distant location and place a healthy hive at the old location, so that the foragers will return to the old site and boost the other hive population. The laying workers should stay with their brood and die out. Of course there will be some workers left with them but hopefully most will reorientate to the new colony at the old site.

Drones from laying workers are haploid just like drones from eggs layed by the queen.
Diploid drones only form when a fertilized egg is homozygous on the complementary sex determiner (csd) gene on chromosome 3. These drones will not develop as the larvae are eaten by workers just after hatching resulting in a shot brood pattern.

I too have not had success with shaking out and requeening. I think the best situation may be to remove the hive to a distant location and place a healthy hive at the old location, so that the foragers will return to the old site and boost the other hive population. The laying workers should stay with their brood and die out. Of course there will be some workers left with them but hopefully most will reorientate to the new colony at the old site.

Seems like a good method to solve this issue, Barbara. Have you tried this yourself?

Apologies for the delayed reply.
It is difficult to assess how successful it actually is or whether it is even worth the effort as the colony is usually pretty depleted of bees by the time laying workers develop, so the workers that migrate to other colonies if you move the hive do not greatly increase the population there and there is always some disruption about "foreign" workers trying to access a hive which can be counter productive. It rarely happens that I am left with a queenless hive that develops laying workers, so I cannot say I have used it more than once as oppose to the several times I have shaken bees out and tried to requeen and been unsuccessful. Either way, the laying worker colony is goosed, so you are only ever trying to salvage what you can from it.... ie a few workers and a bit of comb and whatever honey there is although some of the brood comb with the laying worker drones needs to be cut out and disposed of.... my chickens enjoy the grubs though!

I own a different/alternative method to rectify
this nuisance, I'll have a go at writing it up if
the exercise is still an option.
As Barbara has put.. it is rare as an event in
managed colonies and yes, usually any other
remedy I have tried has failed.

Conserving wild bees

Research suggests that bumble bee boxes have a very low success rate in actually attracting bees into them. We find that if you create an environment where first of all you can attract mice inside, such as a pile of stones, a drystone wall, paving slabs with intentionally made cavities underneath, this will increase the success rate.

Most bumble bee species need a dry space about the size a football, with a narrow entrance tunnel approximately 2cm in diameter and 20 cm long. Most species nest underground along the base of a linear feature such as a hedge or wall. Sites need to be sheltered and out of direct sunlight.